PC97338 datasheet(115/221 Pages) NSC

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• The result phase of any of the following com-

mands started:

— READ DATA, READ DELETED DATA, READ A

TRACK, READ ID

— WRITE DATA, WRITE DELETED

— FORMAT TRACK

— SCAN EQUAL, SCAN EQUAL OR LOW,

SCAN EQUAL OR HIGH

— VERIFY

• Data is being transferred in non-DMA mode, dur-

ing the execution phase of some command.

Interrupts caused by these conditions are cleared au-

tomatically, or by reading or writing information from

or to the Data Register (FIFO).

Command Phase

Execution Phase

Status of interrupt is reported.

Result Phase

When bit 2 of the second command phase byte (ETR)

in the MODE command is set to 1, the track number

is stored as a 12-bit value. See “Bit 0 - Extended

Track Range (ETR)” on page 101.

In this case, a third result byte should be read to hold

the Most Significant Nibble (MSN), i.e., the four most

significant bits, of the number of the current track.

Otherwise (ETR bit in MODE is 0), this command

phase byte is not required. and, only two result phase

bytes should be read.

First Result Phase Byte,

Result Phase Status Register 0

See “Result Phase Status Register 0 (ST0)” on

page 88.

Second Result Phase Byte,

Present Track Number (PTR)

The value in this byte is the number of the current

track.

Third Result Phase Byte,

Bits 7-4 - MSN of Track Number

If the track number is stored as a 12-bit value,

these bits contain the Most Significant Nibble

(MSN), i.e., the four most significant bits, of the

number of the track to seek.

Otherwise (the ETR bit in the MODE command is

0), this result phase byte is not required.

3.6.20 The SET TRACK Command

This command is used to verify (read) or change

(write) the number of the present track.

This command could be useful for recovery from disk

tracking errors, where the true track number could be

read from the disk using the READ ID command, and

used as input to the SET TRACK command to correct

the Present Track number (PTR) stored internally.

Termination of this command does not generate an

interrupt

Command Phase

When bit 2 of the second command phase byte (ETR)

in the MODE command is set to 1, the track number

is stored as a 12-bit value. See “Bit 0 - Extended

Track Range (ETR)” on page 101.

In this case, issue SET TRACK twice - once for the

Most Significant Byte (MSB) of the number of the cur-

rent track and once for the Least Significant Byte

(LSB).

Otherwise (ETR bit in MODE is 0), issue SET TRACK

only once, with bit 2 (MSB) of the second command

phase byte set to 0.

First Command Phase Byte,

Bit 6 - Write Track Number (WNR)

0 - Read the existing track number.

The result phase byte already contains the

track number, and the third byte in the com-

mand phase is a dummy byte.

1 - Change the track number by writing a new val-

ue to the result phase byte.

Second Command Phase Byte

Bits 1,0 - Logical Drive Select (DS1,0)

These bits indicate which logical drive is active.

See “Bits 1,0 - Logical Drive Select (DS1,0)” on

page 96.

7654

3210

0000

1000

7654

3210

Result Phase Status Register 0 (ST0)

Byte of Present Track Number (PTR)

MSN of PTR

0000

7654

3210

WNR

0001

0011

MSB DS1

DS0

Byte of Present Track Number (PTR)

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